Reports from Pakistan say a military tribunal has sentenced to death five naval officers for their involvement in an attack on a Karachi dockyard in September 2014 that left one officer and three attackers dead.

Retired Major Saeed Ahmed said on May 24 that his son, Sub-Lieutenant Hammad Ahmed, and four other naval officers were sentenced on charges including having links with the Islamic State group, mutiny, hatching a conspiracy, and carrying weapons in the dockyard.

Ahmed said his son was convicted last month, but he only became aware of it last week when he visited him in prison.

"My son was denied the right to a fair trial," he added.

Ahmed's lawyer Inam-ur-Rahim said his client was preparing to file an appeal but so far had not been given documentation relating to the case by the military court.